Is it cheaper than sending XML and a stylesheet though?

Further, PDF and server-side are fine for achieving the same display, but it removes the XML of it all - that is to say, someone might be using the raw XML to lower tools, feeds, etc. if XSLT goes away and congress drops the XML links in favor of PDFs etc, that breaks more than just the pretty formatting

1. No, not cheaper, but the incremental cost of server-side rendering is minimal (especially at the low request rates these pages receive)

2. One should still be able to retrieve the raw XML document. It's just that it won't be automatically transformed client-side.